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J D Rabinov

Publications and source records attributed to J D Rabinov.

10 recordsLinked to original sources
PubMed2006

MR spectroscopic changes in the rat hippocampus following proton radiosurgery.

PURPOSE: To identify MR spectroscopic changes in the rat hippocampus following proton radiosurgery. METHODS AND MATERIALS: A group of 12 rats were treated with Bragg peak proton beam irradiation involving the right hippocampus. Single doses of 30 CGE, 50 CGE, 70 CGE, 90 CGE were delivered to groups of 3 animals using single fraction technique. Animals were imaged using a standard 3 T GE Signa MRI at 4 months following treatment. An untreated animal was also studied. A 3'' surface coil was employed to obtain T1 weighted coronal pre- and post-gadolinium images (TR 600 and TE 30) and dual echo T2 weighted coronal images (TR 3000, TE 30/90). Volumetric analysis with custom software was done to evaluate areas of increased signal on T2 weighted images and the development of hydrocephalus was examined. Animals were sacrificed and specimens of the treated hippocampus were harvested for High Resolution Magic Angle Spinning MR Spectroscopy (HRMAS) followed by histopathology of the tissue samples. Peak values of choline, creatine, N-acetyl aspartate and lipids were evaluated and compared. RESULTS: Peak tissue injury occurred in the surviving 90 CGE animal by both T2 weighted and post-gadolinium imaging. Gadolinium enhancement was seen in decreasing volumes of tissue at dosage levels from 90 to 50 CGE. Hydrocephalus was seen on the untreated side in the 90 CGE animal likely because of mass effect, while it was seen in small degrees in the side of treatment in the 70 and 50 CGE animals. Histopathology showed changes at 90 and 70 CGE, but not at 50 or 30 CGE at this time point using H and E stains. HRMAS showed spectroscopic changes in the surviving 90 and 70 CGE animals but not in the 50 and 30 CGE animals. Statistical significance was not reached because of the small sample size. CONCLUSIONS: Following single dose proton radiosurgery of rat hippocampus, HRMAS is able to identify metabolic changes induced by radiation. Studies built on these principles may help develop non-invasive MR spectroscopic methods to distinguish radiation changes from tumor recurrence.

Animals↗
PubMed2004

A modified technique for using elastase to create saccular aneurysms in animals that histologically and hemodynamically resemble aneurysms in human.

BACKGROUND: Treatment of intracranial aneurysms is evolving with the development of novel therapies. It is important to have an animal model which simulates human aneurysms. We describe a new modified technique to the elastase aneurysm model which creates aneurysms that histologically and hemodynamically resemble human aneurysms. METHODS: Twelve New Zealand white rabbits underwent the aneurysm creation procedure, and 2 underwent a control procedure. In the aneurysm creation procedure, the right common carotid artery (RCCA) origin is surgically exposed and temporarily occluded with a temporary aneurysm clip. The RCCA is ligated distally, and the trapped segment is infused with elastase for 20 minutes, after which the clip is removed. In the control procedure, the RCCA is ligated distally with no elastase. Animals were assessed neurologically using a previously described rabbit neurologic grading scale and food intake scale. Intravenous digital subtraction angiography (IVDSA) was performed 21 days after the procedure. Aneurysms were harvested and stained with H&E and Verhoeff's stain. FINDINGS: All 14 rabbits had normal neurologic and food intake assessments. All 12 rabbits that underwent aneurysm creation procedures demonstrated saccular aneurysms on IVDSA. Mean aneurysm size was 5.9+/-1.9 mm; range 4.3-10.8 mm. The close proximity of the LCCA to the origin of the RCCA on the aortic arch of the New Zealand white rabbit closely resembles a bifurcation aneurysm. Both rabbits that underwent control procedures showed no aneurysm and retrograde thrombosis of the RCCA. Histologic analysis showed the aneurysms had histology characteristic of true human aneurysms. CONCLUSION: We have developed a new modified technique to the elastase aneurysm model which creates aneurysms that hemodynamically and histologically resemble human aneurysms. There have been previous elastase models described, however we find our model is easier to perform and highly reproducible. The aneurysms can be accessed transfemorally making the model ideal for testing endovascular therapies.

Animals↗
PubMed2001

Dose-escalation with proton/photon irradiation for Daumas-Duport lower-grade glioma: results of an institutional phase I/II trial.

PURPOSE: The role of dose escalation with proton/photon radiotherapy in lower-grade gliomas was assessed in a prospective Phase I/II trial. We report the results in terms of local control, toxicity, and survival. MATERIALS AND METHODS: Twenty patients with Grade 2/4 (n = 7) and Grade 3/4 (n = 13) gliomas according to the Daumas-Duport classification were treated on a prospective institutional protocol at Massachusetts General Hospital/Harvard Cyclotron Laboratory between 1993 and 1996. Doses prescribed to the target volumes were 68.2 cobalt Gray equivalent (CGE, 1 proton Gray = 1.1 CGE) to gross tumor in Grade 2 lesions and 79.7 CGE in Grade 3 lesions. Fractionation was conventional, with 1.8 to 1.92 CGE once per day. Eligibility criteria included age between 18 and 70 years, biopsy-proven Daumas-Duport Grade 2/4 or 3/4 malignant glioma, Karnofsky performance score of 70 or greater, and supratentorial tumor. Median age of the patient population at diagnosis was 35.9 years (range 19-49). Ten tumors were mixed gliomas, one an oligodendroglioma. RESULTS: Five patients underwent biopsy, 12 a subtotal resection, and 3 a gross total resection. Median interval from surgery to first radiation treatment was 2.9 months. Actuarial 5-year survival rate for Grade 2 lesions was 71% as calculated from diagnosis (median survival not yet reached); actuarial 5-year survival for Grade 3 lesions was 23% (median 29 months). Median follow-up is 61 months and 55 months for 4 patients alive with Grade 2 and 3 patients alive with Grade 3 lesions, respectively. Three patients with Grade 2 lesions died from tumor recurrence, whereas 2 of the 4 survivors have evidence of radiation necrosis. Eight of 10 patients who have died with Grade 3 lesions died from tumor recurrence, 1 from pulmonary embolus, and 1 most likely from radiation necrosis. One of 3 survivors in this group has evidence of radiation necrosis. CONCLUSION: Tumor recurrence was neither prevented nor noticeably delayed in our patients relative to published series on photon irradiation. Dose escalation using this fractionation scheme and total dose delivered failed to improve outcome for patients with Grade 2 and 3 gliomas.

Adult↗
PubMed2000

Imaging of salivary gland pathology.

Calcifications in the salivary glands may occur in calculi, chronic infection or inflammation, phleboliths, lymph nodes, chronic hematoma, amyloidosis, and tumors including pleomorphic adenomas, schwannomas, and mucoepidermoid cancers. This article discusses the different types of salivary gland conditions and the best methods of imaging for diagnosis.

Amyloidosis↗
PubMed1999

Early changes measured by magnetic resonance imaging in cerebral blood flow, blood volume, and blood-brain barrier permeability following dexamethasone treatment in patients with brain tumors.

OBJECT: In this study the authors assessed the early changes in brain tumor physiology associated with glucocorticoid administration. Glucocorticoids have a dramatic effect on symptoms in patients with brain tumors over a time scale ranging from minutes to a few hours. Previous studies have indicated that glucocorticoids may act either by decreasing cerebral blood volume (CBV) or blood-tumor barrier (BTB) permeability and thereby the degree of vasogenic edema. METHODS: Using magnetic resonance (MR) imaging, the authors examined the acute changes in CBV, cerebral blood flow (CBF), and BTB permeability to gadolinium-diethylenetriamine pentaacetic acid after administration of dexamethasone in six patients with brain tumors. In patients with acute decreases in BTB permeability after dexamethasone administration, changes in the degree of edema were assessed using the apparent diffusion coefficient of water. CONCLUSIONS: Dexamethasone was found to cause a dramatic decrease in BTB permeability and regional CBV but no significant changes in CBF or the degree of edema. The authors found that MR imaging provides a powerful tool for investigating the pathophysiological changes associated with the clinical effects of glucocorticoids.

Antineoplastic Agents, Hormonal↗
PubMed1999

Accelerated fractionated proton/photon irradiation to 90 cobalt gray equivalent for glioblastoma multiforme: results of a phase II prospective trial.

OBJECT: After conventional doses of 55 to 65 Gy of fractionated irradiation, glioblastoma multiforme (GBM) usually recurs at its original location. This institutional phase II study was designed to assess whether dose escalation to 90 cobalt gray equivalent (CGE) with conformal protons and photons in accelerated fractionation would improve local tumor control and patient survival. METHODS: Twenty-three patients were enrolled in this study. Eligibility criteria included age between 18 and 70 years, Karnofsky Performance Scale score of greater than or equal to 70, residual tumor volume of less than 60 ml, and a supratentorial, unilateral tumor. Actuarial survival rates at 2 and 3 years were 34% and 18%, respectively. The median survival time was 20 months, with four patients alive 22 to 60 months postdiagnosis. Analysis by Radiation Therapy Oncology Group prognostic criteria or Medical Research Council indices showed a 5- to 11-month increase in median survival time over those of comparable conventionally treated patients. All patients developed new areas of gadolinium enhancement during the follow-up period. Histological examination of tissues obtained at biopsy, resection, or autopsy was conducted in 15 of 23 patients. Radiation necrosis only was demonstrated in seven patients, and their survival was significantly longer than that of patients with recurrent tumor (p = 0.01). Tumor regrowth occurred most commonly in areas that received doses of 60 to 70 CGE or less; recurrent tumor was found in only one case in the 90-CGE volume. CONCLUSIONS: A dose of 90 CGE in accelerated fractionation prevented central recurrence in almost all cases. The median survival time was extended to 20 months, likely as a result of central control. Tumors will usually recur in areas immediately peripheral to this 90-CGE volume, but attempts to extend local control by enlarging the central volume are likely to be limited by difficulties with radiation necrosis.

Actuarial Analysis↗
PubMed1999

Diagnostic imaging of angiographically occult vascular malformations.

Occult vascular malformations of the central nervous system include cavernous malformations, capillary telangiectasis, and developmental venous anomalies (DVAs). Cavernous malformations are prone to multiple small hemorrhages and may enlarge with time. They have a heterogeneous appearance on CT and MR imaging with areas of hemorrhage in various states of evolution and sometimes calcifications. Developmental venous anomalies and capillary telangiectasis are usually incidental findings on imaging studies. They usually are not the cause of pathology by themselves, although DVAs can be associated with cavernous malformations in 8% to 33% of cases.

Arteriovenous Malformations↗
PubMed1998

Extension to the orbit from paraorbital disease. The sinuses.

Disease of the sinuses frequently involves the orbit. Infection, mucocele, and tumor of the sinuses originally may present with orbital findings. Imaging attempts to evaluate the interface between sinus and orbit. Imaging findings reflect the integrity of the sinus mucosa, the thin bony wall, and the more resistant fibrous periorbita. Both CT and MR imaging play a role in this evaluation.

Bacterial Infections↗